It hit me earlier. The way to canonise the time inconsistencies from around the time of Slough's 'second death'.
I'm thinking that Vowzra's disturbed state at the time caused a slight disturbance in the Time stream, meaning that time did not operate properly for everyone from the moment of Slough's death.
When Vowzra died, this was exacerbated. The fact that a plane with vastly different time passage to the rest of the universe was torn in (New Chronos) also added to the imbalance, and now there are some rather large time inconsistencies across the board. This wouldn't be anything anyone would notice immediately, but it provides an explanation for why close to 22 years (an estimate) have passed in Yara's plot since she arrived in Vetros while somewhere else one year or less may have passed.

I'm thinking this instability will be sorted by the end of the Yara storyline (coming soon!) and that can be the next 'global event' from where our new time system can come into effect - once Termite explains it. Thoughts?

Edit: This time inconsistency think only applies to everything happening from the moment of Slough's second death, so any inconsistencies before that will have to be sorted out in a more orthodox manner.